Thanks. I'll weigh my options when I have some more info.
Regearing to 4.88s
- Thread starter RiverRatMatt
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This is a simple middle school math problem. Stock rpms at a given speed * 4.88/4.1 * 31/34. 80mph is approximately 2600rpms. Very smooth and chill for the 4.7
When I looked at the numbers again, I think it may be more like 2800...which is still fine. Your 5th gear is .72, not .71 and your 34s may really be 33.7 or something.
Here is the real formula for you, or anyone,specifically. Your highest gear ratio(.72 for you) times your diff ratio(4.88 proposed) times your specific tire's revs per mile(specs at tire rack or wherever) = revs at 60mph. Multiply that by 1.33 to get 80mph. I have a 99 with 4.88 and 255/85/16 km3 so 33.1 inch...my revs are about 3050 by above calculation and in real world by GPS speed and tach
Here is the real formula for you, or anyone,specifically. Your highest gear ratio(.72 for you) times your diff ratio(4.88 proposed) times your specific tire's revs per mile(specs at tire rack or wherever) = revs at 60mph. Multiply that by 1.33 to get 80mph. I have a 99 with 4.88 and 255/85/16 km3 so 33.1 inch...my revs are about 3050 by above calculation and in real world by GPS speed and tach
Doing some more in-depth research here. Using the formula from @LCReunion 's post above, I come up with:
.72 gear ratio (5-speed) X 4.88 diff X 610 revs per mile (285/75/17; per tirerack) X 1.33 for 80MPH= 2850 RPM at 80 MPH. Using the same formula for my stock gears shows I would be seeing right at 2400RPM at 80. I don't have the truck with me or I'd go confirm.
Sounds pretty reasonable, about the same as just pushing my gear selector into 4th on the highway, which isn't bad at all. I don't tend to drive this truck more than 80-85MPH on the highway, and usually wouldn't even hit 85 unless passing.
Hard to find accounts of guys with the 5-speed and 34s. Most of what's posted is for 4-speeds or 33s/35s. If the truck will run comfortably at 85MPH (which I think it will, based on the above), then I feel that 4.88s will be a fit for my application.
The next question (and this is just talking out loud, I can confirm this info later) is if I'm planning to add lockers at the same time, would I be ordering the 'with' or 'without' OE locker kit? Probably a stupid question, but that's an expensive mistake to make the first time!
.72 gear ratio (5-speed) X 4.88 diff X 610 revs per mile (285/75/17; per tirerack) X 1.33 for 80MPH= 2850 RPM at 80 MPH. Using the same formula for my stock gears shows I would be seeing right at 2400RPM at 80. I don't have the truck with me or I'd go confirm.
Sounds pretty reasonable, about the same as just pushing my gear selector into 4th on the highway, which isn't bad at all. I don't tend to drive this truck more than 80-85MPH on the highway, and usually wouldn't even hit 85 unless passing.
Hard to find accounts of guys with the 5-speed and 34s. Most of what's posted is for 4-speeds or 33s/35s. If the truck will run comfortably at 85MPH (which I think it will, based on the above), then I feel that 4.88s will be a fit for my application.
The next question (and this is just talking out loud, I can confirm this info later) is if I'm planning to add lockers at the same time, would I be ordering the 'with' or 'without' OE locker kit? Probably a stupid question, but that's an expensive mistake to make the first time!
If you are getting aftermarket lockers (ARB, Harrops etc.) then there is no e locker kit. Most of these come with their own wiring harness that is mostly plug and play. Connect the red wire to a power source and put the switch somewhere on the dash and voila! you are locked. Switch in ON position is locked, OFF position is unlocked.
The does mean that you don't have any built in protections of factory locking computer. So you can lock at any speed, whether your transfer case is in low or not and the ability to lock front without locking rear etc. etc.
The does mean that you don't have any built in protections of factory locking computer. So you can lock at any speed, whether your transfer case is in low or not and the ability to lock front without locking rear etc. etc.
I think either the wording or my reading of your first sentence is a little funny. You're saying if I'm going with an aftermarket locker set up, then DO get the non-OE-locker option?
I am likely leaning toward the Harrop e-lockers, so just being sure getting a gear kit for "no e-locker" won't hamper that install.
I am likely leaning toward the Harrop e-lockers, so just being sure getting a gear kit for "no e-locker" won't hamper that install.
Unless you have swapped in a factory Toyota locker at the rear axle, you will not need the E-locker specific install kit. An open diff or any aftermarket locker will use the same "non-OE-locker" kit.
Yup, sounds more like a tractor now...but my radio is still louder, so no big deal
I would agree with you as well (with zero data, but just some logic) that the forces have to go somewhere right. Like say a rear tire of a bike, and the gears are still attached to the hub in exactly the same spot, no matter the reductive gear you choose. You feel less strain, and the wheel is able to be moved at higher loads, but the hub will see proportional stress increases with load increases.
have any of y'all that regeared, done with a thicker oil now? I am using full synth 75/90.
4.88 diff gears plus Tcase underdrive. Been using dino 85w140, even during Colorado winter with zero issues.